**1. Introduction**

Packaging is a crucial part of the food industry because it helps with food handling, storage, transportation, and preservation, as well as protecting against external contaminants, preventing substances inside the food from escaping into the surrounding environment, and reducing food waste [1,2]. Plastic polymers are commonly used for packaging because they are easy to manufacture, inexpensive, printable, and highly resistant to various mechanical and environmental variables [3]. Nevertheless, these packaging substances are harmful to the environment since they take a long time to disintegrate and present the danger of releasing chemicals that might affect food quality [4].

Therefore, the use of biodegradable packaging rather than plastic packaging is encouraged due to environmental and health concerns. Nowadays, the basic substance in biodegradable packaging films is usually derived from natural bio-polymers, such as polysaccharides, lipids, and proteins [5]. These may be recycled, degrade quickly, are non-toxic, and are environment-friendly [6,7].

Chitosan (CH) is the deacetylated chitin derivative and the second most frequent polysaccharide found naturally after cellulose. It is a linear polysaccharide composed of (1,4)-linked 2-amino-deoxy-β-D-glucan [8]. CH has demonstrated benefits in the creation

**Citation:** Elsebaie, E.M.; Mousa, M.M.; Abulmeaty, S.A.; Shaat, H.A.Y.; Elmeslamy, S.A.-E.; Asker, G.A.; Faramawy, A.A.; Shaat, H.A.Y.; Abd Elrahman, W.M.; Eldamaty, H.S.E.; et al. Chitosan-Based Green Pea (*Pisum sativum* L.) Pod Extract Gel Film: Characterization and Application in Food Packaging. *Gels* **2023**, *9*, 77. https://doi.org/10.3390/gels9020077

Academic Editors: Aris Giannakas, Constantinos Salmas and Charalampos Proestos

Received: 29 December 2022 Revised: 13 January 2023 Accepted: 13 January 2023 Published: 18 January 2023

**Copyright:** © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

of biodegradable films because of its unique characteristics, including ease of film formation, nontoxicity, good mechanical strength, excellent barrier capacity, antioxidant activity, biodegradability, and antimicrobial activity [9]. Despite the benefits mentioned above, a pure CH film is frequently fragile, has low force resistance, and is relatively susceptible to moisture [10]. Furthermore, continued development of its antioxidant and antibacterial characteristics is required for active packaging, and therefore, that becomes the focus of attention over time. Many modification procedures have been presented so far, such as the addition of antioxidants, antibacterial compounds, and reinforcing agents to either transmit or enhance certain characteristics of CH-based films [11]. The use of antioxidants in packaging films has grown in popularity since oxidation is a key issue impacting the quality of food. Butylated hydroxyl-toluene (BHT) and butylated hydroxy-anisole (BHA) are the most commonly added antioxidants to active packaging films nowadays [12]. Even though the great stability, low cost, and efficiency of these artificial antioxidants make them an effective choice for active food packaging, there are serious concerns about their toxicological properties [13].

Furthermore, due to the possible health risks posed by these substances, the consumption of artificial antioxidants is strictly regulated. In order to replace artificial antioxidants with natural ones, such as polyphenolic compounds, extensive investigations have been done in this area [14,15]. Several plant extracts have been incorporated into the CH film as a source of antioxidants, such as murta leaf extract [16], sweet potato extract [17], grape seed extract [18], banana peels extract [19], soybean seed coat extract [20], pomegranate peel extract [21], chestnut extract [22], etc., resulting in a boost in the film's antioxidant properties.

Pea *(Pisum sativum)*, sometimes referred to as "Besela" in Egypt, is an annual crop grown during the winter [23]. It is one of Egypt's most significant vegetable crops, and cooked green seeds are one of the most popular foods consumed. Empty pea pods (EPP), which make up between 30 and 67% of the entire weight of the pod, are a by-product of the pea processing sector [24]. Several high-value compounds are abundant in these EPP. They include a high amount of proteins, dietary fibre (over 50%, mostly water-insoluble), iron, potassium, and phenolic components [25]. The latter has significant promise and may be used in the feed, food, pharmaceutical, and cosmetic sectors if it is made from a cheap resource such as EPP [26]. Although the chemical composition of EPP has been extensively studied, little is currently known about its polyphenol compounds. Catechin, epicatechin, gallic acid, and other phenolic components found in abundance in empty pea pod extract (EPPE) provide EPP with a high antioxidant capacity [25,26].

To the best of our knowledge, no studies have been performed on the use of EPP or EPPE as a possible natural addition to boost the antioxidant activity of biodegradable film. Scientific research with the aim of developing active food packaging sheets incorporating EPPE might provide the pea processing sector with a new functionality and turn EPP into a very precious resource. Thus, the current study intended to develop an innovative CH-based active packaging gel film for the first time by incorporating EPPE and to assess the physical, optical, mechanical, morphological, and biological characteristics of the CH films produced. The gel films produced were also assessed as a package for oil storage because of their potential use in slowing the oxidation of corn oil.
